def valid(self):
    if (not self.value):
        return True
    if (self.value in OPENSOURCELICENSES):
        return True
    else:
        return ("Unknown license identifier: '%s'. See https://spdx.org/licenses/" % self.value)
def valid(self):
    if (not self.value):
        return True
    if (self.value in OPENSOURCELICENSES):
        return True
    else:
        return ("Unknown license identifier: '%s'. See https://spdx.org/licenses/" % self.value)