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1. Check external_id is not empty.

   1. In case of error - return 422 (external_id should not be empty)

2. Check external_id is unique ? (unique within le?)

   1. In case of error - return 422 (external_id already exists) ?

Generate person_id

1. Generate person_id (will be returned in response). Ensure there is no such person_id in MPI.persons

2. Generate patient_id to save it in patients collection.

Save object to Mongo DB

Insert patient and set of submitted medical events

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