code: def warn_null_calculation(operation, column):
      warnings.warn(
          'Column "{}" contains nulls. These will be excluded from {} calculation.'.format(
              column.name, operation.__class__.__name__
          ),
          NullCalculationWarning,
          stacklevel=2,
      )
  
file_path: agate/agate/warns.py
imports: import warnings
label_desc: Use image node_id 1 for calling a global function with example usage: warn_null_calculation(operation, column) without return types