<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def convertascii(value, command='to'):
 """ Convert an ASCII value to a symbol :type value: string :param value: The text or the text in ascii form. :type argument: string :param argument: The action to perform on the value. Can be "to" or "from". """

    command = command.lower()
    if command == 'to':
        return chr(value)
    elif command == 'from':
        return ord(value)
    else:
        raise ValueError('Invalid operation provided.')