docs: def load_env(print_vars=False):
      """Load environment variables from a .env file, if present.
  
      If an .env file is found in the working directory, and the listed
      environment variables are not already set, they will be set according to
      the values listed in the file.
      """
      env_file = os.environ.get('ENV_FILE', '.env')
      try:
          variables = open(env_file).read().splitlines()
          for v in variables:
              if '=' in v:
                  key, value = v.split('=', 1)
                  if key.startswith('#'):
                      continue
                  if key not in os.environ:
                      if value.startswith('"') and value.endswith('"') or \
                                      value.startswith("'") and value.endswith("'"):
                          os.environ[key] = ast.literal_eval(value)
                      else:
                          os.environ[key] = value
                      if print_vars:
                          print(key, os.environ[key])
      except IOError:
          pass