code: def field(self, name):
          
          if self.fields.has_key(name):
              return self.fields[name]
          elif self.extends:
              if not self.parent:
                  self.parent = self.contract.struct(self.extends)
              return self.parent.field(name)
          else:
              return None
docs: Returns the field on this struct with the given name. Will try to find this 
          name on all ancestors if this struct extends another.
  
          If found, returns a dict with keys: 'name', 'comment', 'type', 'is_array'
          If not found, returns None
  
          :Parameters:
            name
              string name of field to lookup