code: def validate_signature(self, filename):
          
  
          if not GPG_PRESENT:
              return False
  
          sigfilename = filename + '.sig'
  
          try:
              with open(sigfilename):
                  pass
  
          except IOError:
              # Signature file does not exist
              return False
  
          # Check if the sig is valid for the sigfile
          # TODO: Check for whitespace in filepaths
          return verify(sigfilename, filename)
docs: Returns True if a valid signature is present for filename