#In Chapter $3\mathrm{.}4,$ we wrote a function called find$\_$pressure

#that calculated pressure given number of moles,

#temperature, volume, and optionally, a value for R$.$ If no

#value was given for R$,$ we assumed its value should be

#$0\mathrm{.}082057.$

#

#However, as written, that function could crash: what about

#when the user enters a Volume of $0?$ That would cause a

#ZeroDivisonError! $($In addition to breaking the laws of

#physics, but there's no Python error for that.$)$

#

#Revise that find$\_$pressure function to catch that error. If

#that error occurs, return the string "Volume must be

#greater than $0."$ Otherwise, the function should work just

#as it did before.

#

#Feel free to copy your answer to that exercise and work

#from there. If you'd prefer to start from scratch, remember:

#you're creating a function called find$\_$pressure that returns

#a value for pressure given variables n$,$ T$,$ V$,$ and optionally

#R$,$ according to this formula:

#

# Pressure $=($nRT$)/$ V

#

#You may not use a conditional. R should have a default value

#of $0\mathrm{.}082057.$