<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def indentation(logical_line, previous_logical, indent_char, indent_level, previous_indent_level):
 """ Use 4 spaces per indentation level. For really old code that you don't want to mess up, you can continue to use 8-space tabs. """

    if indent_char == ' ' and indent_level % 4:
        return 0, "E111 indentation is not a multiple of four"
    indent_expect = previous_logical.endswith(':')
    if indent_expect and indent_level <= previous_indent_level:
        return 0, "E112 expected an indented block"
    if indent_level > previous_indent_level and not indent_expect:
        return 0, "E113 unexpected indentation"