def check_extras(dist, attr, value):
 try:
  for (k, v) in value.items():
   if (':' in k):
    (k, m) = k.split(':', 1)
    if pkg_resources.invalid_marker(m):
     raise DistutilsSetupError(('Invalid environment marker: ' + m))
   list(pkg_resources.parse_requirements(v))
 except (TypeError, ValueError, AttributeError):
  raise DistutilsSetupError("'extras_require' must be a dictionary whose values are strings or lists of strings containing valid project/version requirement specifiers.")

def check_extras ( dist , attr , value ) : try : for ( k , v ) in value . items ( ) : if ( ':' in k ) : ( k , m ) = k . split ( ':' , 1 ) if pkg_resources . invalid_marker ( m ) : raise DistutilsSetupError ( ( 'Invalid environment marker: ' + m ) ) list ( pkg_resources . parse_requirements ( v ) ) except ( TypeError , ValueError , AttributeError ) : raise DistutilsSetupError ( "'extras_require' must be a dictionary whose values are strings or lists of strings containing valid project/version requirement specifiers." )
verify that extras_require mapping is valid .