isKeyword( keyword )
    Returns a boolean indicating whether a string is a reserved keyword in the
    REPL environment.

    Parameters
    ----------
    keyword: string
        Keyword to test.

    Returns
    -------
    bool: boolean
        Boolean indicating whether a string is a reserved keyword.

    Examples
    --------
    > isKeyword( 'Float64Array' )
    true
    > isKeyword( 'beep_boop_bop_bip_foo_bar' )
    false

    See Also
    --------
    help, info