code: def _check_at_is_all(method):
      if method["at"] == "all":
          raise ValueError(
              "Only margeff are available when `at` is "
              "'all'. Please input specific points if you would "
              "like to do inference."
          )
  
imports: from statsmodels.compat.python import lzip
  import numpy
  from scipy.stats import norm
  from statsmodels.tools.decorators import cache_readonly
label_desc: Use image node_id 17 for calling a global function with example usage: _check_at_is_all(method) without return types