{{alias}}( str, len[, pad] )
    Left pads a `string` such that the padded `string` has a length of at least
    `len`.

    An output string is not guaranteed to have a length of exactly `len`, but to
    have a length of at least `len`. To generate a padded string having a length
    equal to `len`, post-process a padded string by trimming off excess
    characters.

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

    len: integer
        Minimum string length.

    pad: string (optional)
        String used to pad. Default: ' '.

    Returns
    -------
    out: string
        Padded string.

    Examples
    --------
    > var out = {{alias}}( 'a', 5 )
    '    a'
    > out = {{alias}}( 'beep', 10, 'b' )
    'bbbbbbbeep'
    > out = {{alias}}( 'boop', 12, 'beep' )
    'beepbeepboop'

    See Also
    --------