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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 _commit_change(alias_table, export_path=None, post_commit=True):
 """ Record changes to the alias table. Also write new alias config hash and collided alias, if any. Args: alias_table: The alias table to commit. export_path: The path to export the aliases to. Default: GLOBAL_ALIAS_PATH. post_commit: True if we want to perform some extra actions after writing alias to file. """

    with open(export_path or GLOBAL_ALIAS_PATH, 'w+') as alias_config_file:
        alias_table.write(alias_config_file)
        if post_commit:
            alias_config_file.seek(0)
            alias_config_hash = hashlib.sha1(alias_config_file.read().encode('utf-8')).hexdigest()
            AliasManager.write_alias_config_hash(alias_config_hash)
            collided_alias = AliasManager.build_collision_table(alias_table.sections())
            AliasManager.write_collided_alias(collided_alias)
            build_tab_completion_table(alias_table)