### Building the `first` sets
When calculating what can follow a particular non-terminal, we will need to
-know what the "first" terminal in an subsequent non-terminal might be. So
+know what the "first" terminal in any subsequent non-terminal might be. So
we calculate the `first` set for every non-terminal and store them in an
array. We don't bother recording the "first" set for terminals as they are
trivial.
function reports if it could.
So `shift` finds the next state. If that succeed it extends the allocations
-if needed and pushed all the information onto the stacks.
+if needed and pushes all the information onto the stacks.
###### parser functions