Python Pandas populate column from partial string match

I have a dataframe like below, and I need to create a new column Block with either the value 1 or 2 in it based on a partial string match in the column Program Number where it says _block_1 or _block_2. I've been trying if statements and .str.contains but can't get it to work. How would you do this?

148 0209-3SP_block_1    ['g76p010060q00250r.0005'   'JEBD0507160 REV A' CHNCIII
149 0209-3SP_block_2    ['g76x.3761z-.500p03067q03067f.05'  'JEBD0507160 REV A' CHNC III
150 0209-5SP_block_1    ['g76p020060q00250r.0005'   'JEBD0507160 REV A' CHNC III
151 0209-5SP_block_2    ['g76x.3767z-.48p03067q03067f.05'   'JEBD0507160 REV A' CHNC III
152 0210-3SP_block_1    ['g76p010060q00250r.0005'   'JEBD0507160 REV A' CHNC III

#python #pandas #string