code: def linkcode_resolve(domain, info):
      
      if domain != 'py':
          return None
  
      modname = info['module']
      fullname = info['fullname']
  
      submod = sys.modules.get(modname)
      if submod is None:
          return None
  
      obj = submod
      for part in fullname.split('.'):
          try:
              obj = getattr(obj, part)
          except AttributeError:
              return None
  
      try:
          # inspect.unwrap() was added in Python version 3.4
          if sys.version_info >= (3, 5):
              fn = inspect.getsourcefile(inspect.unwrap(obj))
          else:
              fn = inspect.getsourcefile(obj)
      except TypeError:
          fn = None
      if not fn:
          return None
  
      try:
          source, lineno = inspect.getsourcelines(obj)
      except OSError:
          lineno = None
  
      if lineno:
          linespec = "#L{:d}-L{:d}".format(lineno, lineno + len(source) - 1)
      else:
          linespec = ""
  
      fn = os.path.relpath(fn, start=os.path.dirname(pandas.__file__))
  
      if '+' in pandas.__version__:
          return ("http://github.com/pandas-dev/pandas/blob/master/pandas/"
                  "{}{}".format(fn, linespec))
      else:
          return ("http://github.com/pandas-dev/pandas/blob/"
                  "v{}/pandas/{}{}".format(pandas.__version__, fn, linespec))
docs: Determine the URL corresponding to Python object