{{alias}}( str )
    Tests whether a string contains only numeric digits.

    Parameters
    ----------
    str: string
        Input string.

    Returns
    -------
    bool: boolean
        Boolean indicating whether a string contains only numeric digits.

    Examples
    --------
    > var bool = {{alias}}( '0123456789' )
    true
    > bool = {{alias}}( 'abcdef' )
    false
    > bool = {{alias}}( '0xff' )
    false
    > bool = {{alias}}( '' )
    false

    See Also
    --------