{{alias}}( str, pos )
    Tests if a position in a string marks the start of a UTF-16 surrogate pair.

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

    pos: integer
        Position.

    Returns
    -------
    bool: boolean
        Boolean indicating whether surrogate pair exists at specified position.

    Examples
    --------
    > var out = {{alias}}( '🌷', 0 )
    true
    > out = {{alias}}( '🌷', 1 )
    false

    See Also
    --------