I work for a transportation company. On a spreadsheet, I have a list of
Shippers, beside that, I have a list of unique SKUs that the coresponding
shipper carried. Beside that, I have the coresponding Bill of Lading (BOL)
that the Carrier took that SKU out on. I need to count how many times a
particular shipper had a unique BOL.

In the example below, I need the formula to return that there were 2 BOLs
associated with AVRT. I don't need to know what numbers they are or what SKUs
were on them, but I need to know how many shipments there were.

Shipper SKU BOL
AVRT asd 123
AVRT sfg 123
GST dgh 345
JBH ert 876
GST sdf 645
AVRT ghj 875
AVRT skr 875

Thank You!