<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def decamel_to_snake(string):
 """Convert to lower case, join camel case with underscore. CamelCase -> camel_case. Camel Case -> camel_case. """

    strings = [decamel(word) if not word.isupper() else word.lower()
               for word in string.split()]
    return "_".join([snake(dstring)for dstring in strings])