class_docstr: Returns the two digit prefix of a given postal code.
  
  Description:
      Given a list of postal codes, returns the two digit prefix for each postal code.
  
  Examples:
      >>> two_digit_postal_code = TwoDigitPostalCode()
      >>> two_digit_postal_code(['92432', '34514']).tolist()
      ['92', '34']
code: def get_function(self):
      def two_digit_postal_code(postal_codes):
          def transform_postal_code(pc):
              return str(pc)[:2] if pd.notna(pc) else pd.NA
  
          return postal_codes.apply(transform_postal_code)
  
      return two_digit_postal_code
  
file_path: featuretools/featuretools/primitives/standard/transform/postal/two_digit_postal_code.py
imports: import pandas
  from woodwork.column_schema import ColumnSchema
  from woodwork.logical_types import Categorical, PostalCode
  from featuretools.primitives.base import TransformPrimitive
  from featuretools.utils.gen_utils import Library
label_desc: Use image node_id 1 for calling the TwoDigitPostalCode obj's underlying member method code with example usage: obj.get_function() and returns: two_digit_postal_code, postal_codes, unknown