python
import datetime as dt

# Anchor our processing to right now
process_until = dt.datetime.now()

# Process in batches, but only up to our anchored time
limit = 100  # Process 100 calls at a time
while True:
    calls_batch = vapi_client.calls.list(
        limit=limit,
        created_at_lt=process_until  # Don't process calls newer than when we started
    )
    if not calls_batch:  # No more calls to process
        break
        
    for call in calls_batch:
        cost_data = {
            'call_id': call.get('id'),
            'total': call.get('cost', 0),
            'breakdown': call.get('costBreakdown', {})
        }
        # Process each call's cost data immediately
        # instead of keeping everything in memory