Define a function subbag that determines whether or not its first argument bag is contained in the second. Note that a bag b is contained in a bag b' if every element that occurs n times in b occurs also at least n times in b'. Implement it in Haskell programming language.

subbag [] []	= True
subbag [(7,2)] [(7,2)]	= True

subbag [(7,2)] [(7,2),(8,1)]	= True
subbag [(7,2)] [(7,1),(8,1)]	= False

Note: Implement in Haskell only.