<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def extract_edus(merge_file_str):
 """Extract EDUs from DPLPs .merge output files. Returns ------- edus : dict from EDU IDs (int) to words (list(str)) """

        lines = merge_file_str.splitlines()

        edus = defaultdict(list)
        for line in lines:
            if line.strip():  # ignore empty lines
                token = line.split('\t')[2]
                edu_id = int(line.split('\t')[9])
                edus[edu_id].append(token)
        return edus