code: def check_is_declared_explicit(lineno, id_, classname='variable'):
      
      if not config.OPTIONS.explicit.value:
          return True
  
      entry = global_.SYMBOL_TABLE.check_is_declared(id_, lineno, classname)
      return entry is not None
docs: Check if the current ID is already declared.
      If not, triggers a "undeclared identifier" error,
      if the --explicit command line flag is enabled (or #pragma
      option strict is in use).
  
      If not in strict mode, passes it silently.