code: def as_command(self, sock_info):
          
          # We use the command twice: on the wire and for command monitoring.
          # Generate it once, for speed and to avoid repeating side-effects.
          if self._as_command is not None:
              return self._as_command
  
          explain = '$explain' in self.spec
          cmd = _gen_find_command(
              self.coll, self.spec, self.fields, self.ntoskip,
              self.limit, self.batch_size, self.flags, self.read_concern,
              self.collation, self.session)
          if explain:
              self.name = 'explain'
              cmd = SON([('explain', cmd)])
          session = self.session
          if session:
              session._apply_to(cmd, False, self.read_preference)
              # Explain does not support readConcern.
              if (not explain and session.options.causal_consistency
                      and session.operation_time is not None
                      and not session._in_transaction):
                  cmd.setdefault(
                      'readConcern', {})[
                      'afterClusterTime'] = session.operation_time
          sock_info.send_cluster_time(cmd, session, self.client)
          self._as_command = cmd, self.db
          return self._as_command
docs: Return a find command document for this query.