class_docstr: A collection of protobufs dynamically constructed by descriptor protos.
class_docstr_tok: ["A","collection","of","protobufs","dynamically","constructed","by","descriptor","protos","."]
docstr: Loads the named extension descriptor from the pool.
  
  Args:
    full_name (str): The full name of the extension descriptor to load.
  
  Returns:
    FieldDescriptor: The field descriptor for the named extension.
  
  Raises:
    KeyError: if the extension cannot be found in the pool.
code: def FindExtensionByName(self, full_name):
      """Loads the named extension descriptor from the pool.
  
      Args:
        full_name (str): The full name of the extension descriptor to load.
  
      Returns:
        FieldDescriptor: The field descriptor for the named extension.
  
      Raises:
        KeyError: if the extension cannot be found in the pool.
      """
      full_name = _NormalizeFullyQualifiedName(full_name)
      try:
          # The proto compiler does not give any link between the FileDescriptor
          # and top-level extensions unless the FileDescriptorProto is added to
          # the DescriptorDatabase, but this can impact memory usage.
          # So we registered these extensions by name explicitly.
          return self._toplevel_extensions[full_name]
      except KeyError:
          pass
      message_name, _, extension_name = full_name.rpartition(".")
      try:
          # Most extensions are nested inside a message.
          scope = self.FindMessageTypeByName(message_name)
      except KeyError:
          # Some extensions are defined at file scope.
          scope = self._FindFileContainingSymbolInDb(full_name)
      return scope.extensions_by_name[extension_name]
  
imports: import collections
  import warnings
  from google.protobuf import descriptor
  from google.protobuf import descriptor_database
  from google.protobuf import text_encoding
label_desc: Use image node_id 23 for calling the DescriptorPool obj's underlying member method code with example usage: obj.FindExtensionByName(full_name) and returns: scope, self