human
Solve the following python programming problem given the following code:
def apply_path_aliases(cov, aliases) : 
    'Adjust filenames in coverage data.' 
    aliases = sorted (aliases.items (), key = (lambda i : len (i [0])), reverse = True) 
    def fixup_filename(filename) : 
        for (alias, local) in aliases : 
            if filename.startswith (alias) : 
                return (local + filename [len (alias) :]) 
return filename 
cov.data.lines = map_and_merge_dict_keys (fixup_filename, aliases.data.lines) 
    cov.data.arcs = map_dict_keys (fixup_filename, cov.data.arcs) 

    
    

    Fix the buggy line: cov.data.lines = map_and_merge_dict_keys (fixup_filename, aliases.data.lines)
assistant
#Here is Python program to fix the buggy line: cov.

cov.data.lines = map_and_merge_dict_keys (fixup_filename, cov.data.lines)