class_docstr: Base class for attribute collector subclasses. Classes that inherit
  this class may use a declarative syntax to specify which vertex or edge
  attributes they intend to collect. See L{AttributeCollectorMeta} for
  the details.
code: def __len__(self):
      return len(self.seq)
  
file_path: python-igraph/src/igraph/drawing/metamagic.py
imports: from configparser import NoOptionError
  from igraph.configuration import Configuration
label_desc: Use image node_id 4 for calling the AttributeCollectorBase obj's underlying member method code with example usage: obj.__len__() and returns: len