class Protobuf::Message

def get_ext_field(tag_or_name)

TODO merge to get_field 
def get_ext_field(tag_or_name)
  case tag_or_name
  when Integer        then get_ext_field_by_tag(tag_or_name)
  when String, Symbol then get_ext_field_by_name(tag_or_name)
  else                     raise TypeError, tag_or_name.class
  end
end