<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def to_alu_hlu_map(input_str):
 """Converter for alu hlu map Convert following input into a alu -> hlu map: Sample input: ``` HLU Number ALU Number 0 12 1 23 ``` ALU stands for array LUN number hlu stands for host LUN number :param input_str: raw input from naviseccli :return: alu -> hlu map """

    ret = {}
    if input_str is not None:
        pattern = re.compile(r'(\d+)\s*(\d+)')
        for line in input_str.split('\n'):
            line = line.strip()
            if len(line) == 0:
                continue
            matched = re.search(pattern, line)
            if matched is None or len(matched.groups()) < 2:
                continue
            else:
                hlu = matched.group(1)
                alu = matched.group(2)
                ret[int(alu)] = int(hlu)
    return ret