GNU Parallel Bug Reports parallel can't ressigned variablen in the same context in same file

[gmail]

hello
is it a bug to parallel or parallel can't do like this ?

today , i used  parallel to my shell script ,but read all the 
document,no referent  about variable ouside parallel.

bash test code like that:

###################
#!/bin/bash

foo=33

parallel "foo=44;echo $foo;"

above code response 44
####################


best regrade ahead