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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 migrateFileFields(portal):
 """ This function walks over all attachment types and migrates their FileField fields. """

    portal_types = [
        "Attachment",
        "ARImport",
        "Instrument",
        "InstrumentCertification",
        "Method",
        "Multifile",
        "Report",
        "ARReport",
        "SamplePoint"]

    for portal_type in portal_types:
        # Do the migration
        migrate_to_blob(
            portal,
            portal_type=portal_type,
            remove_old_value=True)