def normalize_prefix(path):
if path is None or path is '<STR_LIT>' or path is '<STR_LIT:/>':<EOL><INDENT>return None<EOL><DEDENT>elif path.endswith('<STR_LIT:/>'):<EOL><INDENT>return path<EOL><DEDENT>else:<EOL><INDENT>return path + '<STR_LIT:/>'<EOL><DEDENT>
Add trailing slash to prefix if it is not present

    >>> normalize_prefix("somepath")
    'somepath/'
    >>> normalize_prefix("somepath/")
    'somepath/'