code: def build_request(doc):
      """
      Request format is simple: one tree per sentence in the document
      """
      request = DependencyConverterRequest()
      for sentence in doc.sentences:
          request.trees.append(build_tree(sentence.constituency, None))
      return request
  
file_path: stanza/stanza/server/dependency_converter.py
imports: import stanza
  from stanza.protobuf import DependencyConverterRequest, DependencyConverterResponse
  from stanza.server.java_protobuf_requests import send_request, build_tree, JavaProtobufContext
label_desc: Use image node_id 2 for calling a global function with example usage: build_request(doc) and returns: request