code: def remove_first_two_letters_from_col_names(df):
      """Helper function to mutate dataframe by changing column names."""
      col_names = df.columns
      col_names = [name[2:] for name in col_names]
      df.columns = col_names
      return df
  
file_path: pyjanitor/tests/functions/test_also.py
imports: from unittest.mock import Mock
  import pytest
label_desc: Use image node_id 1 for calling a global function with example usage: remove_first_two_letters_from_col_names(df) and returns: df