class_docstr: Mathematics domain.
code: def note_equation(
      self, docname: str, labelid: str, location: Any = None
  ) -> None:
      if labelid in self.equations:
          other = self.equations[labelid][0]
          logger.warning(
              __("duplicate label of equation %s, other instance in %s")
              % (labelid, other),
              location=location,
          )
  
      self.equations[labelid] = (
          docname,
          self.env.new_serialno("eqno") + 1,
      )
  
imports: from __future__ import annotations
  from typing import TYPE_CHECKING, Any
  from docutils import nodes
  from docutils.nodes import Element, Node, make_id, system_message
  from sphinx.domains import Domain
  from sphinx.locale import __
  from sphinx.roles import XRefRole
  from sphinx.util import logging
  from sphinx.util.nodes import make_refnode
label_desc: Use image node_id 2 for calling the MathDomain obj's underlying member method code with example usage: obj.note_equation(docname, labelid, location) without return types