def ljust(text, width, fillchar=' '):
    """
    Creates a copy of ``text`` left justified in a string of length ``width``. 
    
    Padding is done using the specified ``fillchar`` (default is an ASCII space). The original 
    string is returned if ``width`` is less than or equal to len(s).
    
    :param text: The string to justify
    :type text:  ``str``
    
    :return: A copy of ``text`` left justified in a string of length ``width``.
    :rtype:  ``str``
    """
    assert isinstance(text, str), '%s is not a string' % text
    return text.ljust(width, fillchar)
