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import json
from itertools import islice
                
TAG_FIELD_LENGTH = 4
LENGTH_FIELD_LENGTH = 3
          
def tlv_parser(tlv_string, title):
    tlv = iter(tlv_string)
    result = None
    for tag in iter(lambda: "".join(islice(tlv, TAG_FIELD_LENGTH)), ''):
        length = "".join(islice(tlv, LENGTH_FIELD_LENGTH))
        value = "".join(islice(tlv, int(length)))
        
        if tag == title:
            result = tag + length + value
            break
                            
    if result is not None:
            return result
    else:
            return None