code: def from_string(status_str):
      if status_str not in SourceType._STRING_TO_SOURCETYPE:
          raise Exception(
              f"Could not get run status corresponding to string {status_str}. Valid run "
              f"status strings: {list(SourceType._STRING_TO_SOURCETYPE.keys())}"
          )
      return SourceType._STRING_TO_SOURCETYPE[status_str]
  
label_desc: Use image node_id 1 for calling the SourceType obj's underlying member method code with example usage: obj.from_string(status_str) and returns: SourceType