code: def compute_indel_length(fs_df):
      
      indel_len = pd.Series(index=fs_df.index)
      indel_len[fs_df['Reference_Allele']=='-'] = fs_df['Tumor_Allele'][fs_df['Reference_Allele']=='-'].str.len()
      indel_len[fs_df['Tumor_Allele']=='-'] = fs_df['Reference_Allele'][fs_df['Tumor_Allele']=='-'].str.len()
      indel_len = indel_len.fillna(0).astype(int)
      return indel_len
docs: Computes the indel length accounting for wether it is an insertion or
      deletion.
  
      Parameters
      ----------
      fs_df : pd.DataFrame
          mutation input as dataframe only containing indel mutations
  
      Returns
      -------
      indel_len : pd.Series
          length of indels