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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def find_file_in_load_dirs(relpath):
 """If given relative path exists in one of DevAssistant load paths, return its full path. Args: relpath: a relative path, e.g. "assitants/crt/test.yaml" Returns: absolute path of the file, e.g. "/home/x/.devassistant/assistanta/crt/test.yaml or None if file is not found """

    if relpath.startswith(os.path.sep):
        relpath = relpath.lstrip(os.path.sep)

    for ld in settings.DATA_DIRECTORIES:
        possible_path = os.path.join(ld, relpath)
        if os.path.exists(possible_path):
            return possible_path