def merge_dictionaries(base_dictionary, dict_to_be_merged):
    """Merge two dictionaries into one.

    Args:
        base_dictionary (dict): First Dictionary
        dict_to_be_merged (dict): Seconde Dictionary.

    Returns:
        (dict): Merged dictionaries.
    """
    for key in dict_to_be_merged.keys():
        if key in base_dictionary:
            base_dictionary[key] = base_dictionary[key] + \
                dict_to_be_merged[key]
        else:
            base_dictionary[key] = dict_to_be_merged[key]

    return base_dictionary