import itertools


def combine_list_values_in_dict(expression_dict):
  """Combines list values in a dictionary into a single list.

  Args:
    expression_dict: A dictionary, where each key is a simplified expression and
      the value is a list/Numpy array of expressions with the simplified
      expression.

  Returns:
    List of all expressions combined from the values of the input dictionary.
  """
  return list(itertools.chain(*expression_dict.values()))