def IsPureVirtual(fname):
    """
    Returns true if a header file is a pure virtual (no implementation)
    Pure virtual header files are designated as such by the phrase "Pure virtual"
    at the first line
    Input:
    fname - File name
    """

    f = open(fname)
    fl = f.readline()
    f.close()
    return fl.find('Pure virtual')>-1