code: def get_field_offset(self, name):
      if name not in self._name_offset_mapping:
          raise ValueError(f"{name} does not exist in schema")
  
      return self._name_offset_mapping[name]
  
imports: import copy
  from typing import List, Union
  import pandas
  from .utils import AnonymousGenerator
label_desc: Use image node_id 17 for calling the SchemaManager obj's underlying member method code with example usage: obj.get_field_offset(name) and returns: self