{{alias}}( x, dim, writable )
    Expands the shape of an array by inserting a new dimension of size one at a
    specified dimension index.

    A provided dimension index must reside on the interval `[-N-1, N]`, where
    `N` is the rank (i.e., number of dimensions) of the provided input array.

    If provided a negative dimension index, the position at which to insert a
    singleton dimension is computed as `N + dim + 1`. Hence, if provided `-1`,
    the resolved position is `N` (i.e., a singleton dimension is appended to the
    input array).

    The `writable` parameter only applies to ndarray constructors supporting
    read-only instances.

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

    dim: integer
        Dimension index at which to insert a singleton dimension.

    writable: boolean
        Boolean indicating whether the returned ndarray should be writable.

    Returns
    -------
    out: ndarray
        Output array.

    Examples
    --------
    > var x = {{alias:@stdlib/ndarray/array}}( [ [ 1, 2 ], [ 3, 4 ] ] )
    <ndarray>[ [ 1, 2 ], [ 3, 4 ] ]
    > var y = {{alias}}( x, 1, false )
    <ndarray>[ [ [ 1, 2 ] ], [ [ 3, 4 ] ] ]

    See Also
    --------