code: def set_pkg_license_from_file(self, doc, lic):
          
          self.assert_package_exists()
          if validations.validate_lics_from_file(lic):
              doc.package.licenses_from_files.append(lic)
              return True
          else:
              raise SPDXValueError('Package::LicensesFromFile')
docs: Adds a license from a file to the package.
          Raises SPDXValueError if data malformed.
          Raises OrderError if no package previously defined.