code: def _config_inited(app, config):
      # Check for srcset hidpi images
      for i, size in enumerate(app.config.mathmpl_srcset):
          if size[-1] == "x":  # "2x" = "2.0"
              try:
                  float(size[:-1])
              except ValueError:
                  raise ConfigError(
                      f"Invalid value for mathmpl_srcset parameter: {size!r}. "
                      "Must be a list of strings with the multiplicative "
                      'factor followed by an "x".  e.g. ["2.0x", "1.5x"]'
                  )
          else:
              raise ConfigError(
                  f"Invalid value for mathmpl_srcset parameter: {size!r}. "
                  "Must be a list of strings with the multiplicative "
                  'factor followed by an "x".  e.g. ["2.0x", "1.5x"]'
              )
  
imports: import hashlib
  from pathlib import Path
  from docutils import nodes
  from docutils.parsers.rst import Directive, directives
  import sphinx
  from sphinx.errors import ConfigError, ExtensionError
  import matplotlib
  from matplotlib import _api, mathtext
  from matplotlib.rcsetup import validate_float_or_None
label_desc: Use image node_id 5 for calling a global function with example usage: _config_inited(app, config) without return types