def header_value(headers, name):
 name = name.lower()
 result = [value for (header, value) in headers if (header.lower() == name)]
 if result:
  return ','.join(result)
 else:
  return None

def header_value ( headers , name ) : name = name . lower ( ) result = [ value for ( header , value ) in headers if ( header . lower ( ) == name ) ] if result : return ',' . join ( result ) else : return None
returns the headers value .