old_contents: """Utils."""
  
  from base64 import b64encode
  
  import pandas as pd
  
  
  def dataframe_to_base64(df: pd.DataFrame) -> str:
      """Converts a dataframe to a base64-encoded CSV representation of that data.
  
      This is useful for building datauris for use to download the data in the browser.
  
      Arguments:
          df: The dataframe to convert
      """
      csv = df.to_csv(index=False)
      b64 = b64encode(csv.encode()).decode()
      return b64
  
  
  def excel_to_base64(str_excel_filename) -> str:
      data = open(str_excel_filename, 'rb').read()
      b64 = b64encode(data).decode()
      return b64
  
new_contents: """Utils."""
  
  from base64 import b64encode
  
  import pandas as pd
  
  
  def dataframe_to_base64(df: pd.DataFrame) -> str:
      """Converts a dataframe into csv base64-encoded data.
  
      This is useful for building datauris for use to download the data in the browser.
  
      Arguments:
          df: The dataframe to convert
      """
      csv = df.to_csv(index=False)
      b64 = b64encode(csv.encode()).decode()
      return b64
  
  
  def excel_to_base64(filename: str) -> str:
      """Converts an excel document into base64-encoded data."""
      with open(filename, 'rb') as fin:
          return b64encode(fin.read()).decode()
  
subject: Update excel_to_base64 to always close file handles