+ @classmethod
+ def reject_msgs(cls, has):
+ if len(cls.requires) != len([x for x in cls.requires if has[x]]):
+ yield "lack of required files for format %s" % cls.name
+
+ for key in cls.disallowed:
+ if has[key]:
+ yield "contains source files not allowed in format %s" % cls.name
+
+ @classmethod
+ def validate_format(cls, format, is_a_dsc=False, field='files'):
+ """
+ Raises UnknownFormatError if the specified format tuple is not valid for
+ this format (for example, the format (1, 0) is not valid for the
+ "3.0 (quilt)" format). Return value is undefined in all other cases.
+ """
+ pass
+
+class FormatOne(SourceFormat):