{{alias}}( x[, options] )
    Wraps a provided array as an ndarray index object.

    ndarray index instances have no explicit functionality; however, they are
    used by "fancy" ndarrays for element retrieval and assignment.

    By default, an instance is invalidated and removed from an internal cache
    immediately after a consumer resolves the underlying data associated with an
    instance using the `get` static method. Immediate invalidation and cache
    removal ensures that references to the underlying ndarray are not the source
    of memory leaks.

    Because instances leverage an internal cache implementing the Singleton
    pattern, one must be sure to use the same constructor as consumers. If one
    uses a different constructor, the consumer will *not* be able to resolve the
    original wrapped ndarray, as the consumer will attempt to resolve an
    instance in the wrong internal cache.

    Because non-persisted instances are freed after first use, in order to avoid
    holding onto memory and to allow garbage collection, one should avoid
    scenarios in which an instance is never used.

    Parameters
    ----------
    x: ndarray
        Input ndarray.

    options: Object (optional)
        Function options.

    options.persist: boolean (optional)
        Boolean indicating whether to continue persisting an index object after
        first usage. Default: false.

    options.kind: string (optional)
        Specifies whether a provided ndarray is a specialized input ndarray
        "kind". This option is only applicable for integer input ndarrays. Must
        be one of the following:

        - cartesian: a provided input ndarray contains Cartesian indices.
        - linear: a provided input ndarray contains indices representing
          locations in linear memory.

        Default: ''.

    Returns
    -------
    out: ndindex
        Index instance.

    Examples
    --------
    > var x = {{alias:@stdlib/ndarray/empty}}( [ 2, 2 ], { 'dtype': 'int32' } );
    > var idx = new {{alias}}( x );


{{alias}}.free( id )
    Frees the instance associated with a provided identifier.

    Parameters
    ----------
    id: string
        Instance identifier.

    Returns
    -------
    out: boolean
        Boolean indicating whether an instance was successfully freed.

    Examples
    --------
    > var x = {{alias:@stdlib/ndarray/empty}}( [ 2, 2 ], { 'dtype': 'int32' } );
    > var idx = new {{alias}}( x );
    > {{alias}}.free( idx.id )
    <boolean>


{{alias}}.get( id )
    Returns the ndarray associated with the instance having a provided
    identifier.

    Parameters
    ----------
    id: string
        Instance identifier.

    Returns
    -------
    out: Object
        Object containing ndarray data.

    out.data: ndarray
        The underlying ndarray associated with the provided identifier.

    out.type: string
        The type of ndarray index.

    out.dtype: string
        The data type of the underlying ndarray.

    Examples
    --------
    > var x = {{alias:@stdlib/ndarray/empty}}( [ 2, 2 ], { 'dtype': 'int32' } );
    > var idx = new {{alias}}( x );
    > {{alias}}.get( idx.id )
    {...}


{{alias}}.cartesianIndex( x[, options] )
    Returns an ndarray index containing Cartesian indices.

    This is a convenience method for calling `{{alias}}` with `kind` set to
    'cartesian'.

    Parameters
    ----------
    x: ndarray
        Input ndarray.

    options: Object (optional)
        Function options.

    options.persist: boolean (optional)
        Boolean indicating whether to continue persisting an index object after
        first usage. Default: false.

    Returns
    -------
    out: ndindex
        Index instance.

    Examples
    --------
    > var x = {{alias:@stdlib/ndarray/empty}}( [ 2, 2 ], { 'dtype': 'int32' } );
    > var idx = {{alias}}.cartesianIndex( x );


{{alias}}.linearIndex( x[, options] )
    Returns an ndarray index for indices representing locations in linear
    memory.

    This is a convenience method for calling `{{alias}}` with `kind` set to
    'linear'.

    Parameters
    ----------
    x: ndarray
        Input ndarray.

    options: Object (optional)
        Function options.

    options.persist: boolean (optional)
        Boolean indicating whether to continue persisting an index object after
        first usage. Default: false.

    Returns
    -------
    out: ndindex
        Index instance.

    Examples
    --------
    > var x = {{alias:@stdlib/ndarray/empty}}( [ 5 ], { 'dtype': 'int32' } );
    > var idx = {{alias}}.linearIndex( x );


{{alias}}.prototype.data
    Read-only property returning an ndarray view of the underlying index
    ndarray.

    Returns
    -------
    out: ndarray
        Array data.

    Examples
    --------
    > var x = {{alias:@stdlib/ndarray/empty}}( [ 2, 2 ], { 'dtype': 'int32' } );
    > var idx = new {{alias}}( x );
    > idx.data
    <ndarray>


{{alias}}.prototype.dtype
    Read-only property returning the underlying data type of the index ndarray.

    Returns
    -------
    out: string
        Array data type.

    Examples
    --------
    > var x = {{alias:@stdlib/ndarray/empty}}( [ 2, 2 ], { 'dtype': 'int32' } );
    > var idx = new {{alias}}( x );
    > idx.dtype
    'int32'


{{alias}}.prototype.id
    Read-only property returning the unique identifier associated with an
    instance.

    Returns
    -------
    out: string
        String identifier.

    Examples
    --------
    > var x = {{alias:@stdlib/ndarray/empty}}( [ 2, 2 ], { 'dtype': 'int32' } );
    > var idx = new {{alias}}( x );
    > idx.id
    <string>


{{alias}}.prototype.isCached
    Read-only property returning a boolean indicating whether an ndarray index
    is actively cached.

    Returns
    -------
    out: boolean
        Boolean indicating whether an ndarray index is actively cached.

    Examples
    --------
    > var x = {{alias:@stdlib/ndarray/empty}}( [ 2, 2 ], { 'dtype': 'int32' } );
    > var idx = new {{alias}}( x );
    > idx.isCached
    true


{{alias}}.prototype.kind
    Read-only property returning the ndarray index kind.

    Returns
    -------
    out: string
        Index kind.

    Examples
    --------
    > var x = {{alias:@stdlib/ndarray/empty}}( [ 2, 2 ], { 'dtype': 'int32' } );
    > var idx = new {{alias}}( x, { 'kind': 'cartesian' } );
    > idx.kind
    'cartesian'


{{alias}}.prototype.type
    Read-only property returning the ndarray index type.

    Returns
    -------
    out: string
        Index type.

    Examples
    --------
    > var x = {{alias:@stdlib/ndarray/empty}}( [ 2, 2 ], { 'dtype': 'int32' } );
    > var idx = new {{alias}}( x );
    > idx.type
    <string>


{{alias}}.prototype.toString()
    Serializes an instance as a string.

    Returns
    -------
    str: string
        Serialized string.

    Examples
    --------
    > var x = {{alias:@stdlib/ndarray/empty}}( [ 2, 2 ], { 'dtype': 'int32' } );
    > var idx = new {{alias}}( x );
    > idx.toString()
    <string>


{{alias}}.prototype.toJSON()
    Serializes an instance as a JSON object.

    Returns
    -------
    obj: Object
        JSON object.

    Examples
    --------
    > var x = {{alias:@stdlib/ndarray/empty}}( [ 2, 2 ], { 'dtype': 'int32' } );
    > var idx = new {{alias}}( x );
    > idx.toJSON()
    { 'type': 'ndindex', ... }

    See Also
    --------