class ApprovalError(Exception):
    http_status = 400
    reason_code = "error"


class NotFound(ApprovalError):
    http_status = 404
    reason_code = "not_found"


class Conflict(ApprovalError):
    http_status = 409
    reason_code = "conflict"


class DuplicateApprover(ApprovalError):
    http_status = 409
    reason_code = "duplicate_approver"


class Unprocessable(ApprovalError):
    http_status = 422
    reason_code = "unprocessable"


class StoreUnavailable(ApprovalError):
    http_status = 503
    reason_code = "store_unavailable"