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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 ListMigrationsToProcess(migrations_root, current_migration_number ):
 """Lists filenames of migrations with numbers bigger than a given one."""

  migrations = []
  for m in os.listdir(migrations_root):
    if (current_migration_number is None or
        _MigrationFilenameToInt(m) > current_migration_number):
      migrations.append(m)

  return sorted(migrations, key=_MigrationFilenameToInt)