'Load data from filename'

def load_data(self, filename, ext):

    glbs = self._mglobals()
    load_func = iofunctions.load_funcs[ext]
    (data, error_message) = load_func(filename)
    if error_message:
        return error_message
    for key in list(data.keys()):
        new_key = fix_reference_name(key, blacklist=list(glbs.keys()))
        if (new_key != key):
            data[new_key] = data.pop(key)
    try:
        glbs.update(data)
    except Exception as error:
        return str(error)
    return None
