def parseLineForExpression(line):
    """Return parsed SPDX expression if tag found in line, or None otherwise."""
    p = line.partition("SPDX-License-Identifier:")
    if p[2] == "":
        return None
    # strip away trailing comment marks and whitespace, if any
    expression = p[2].strip()
    expression = expression.rstrip("/*")
    expression = expression.strip()
    return expression