R help - Dec 2011 - MAC Problem with http in R while not problem on Win machine

Hello,

thanks to (http://timelyportfolio.blogspot.com/) and also
(http://systematicinvestor.wordpress.com) the following code was published and
it is running smoothly on my Windows enviroment but it is failing to perform on
my MAC.

#get MAImp code from GIST
#thanks to http://systematicinvestor.wordpress.com
#for showing me how to do this
con=url("https://raw.github.com/gist/1405187/92e7c24ff2459a0830c45b828f1dba41143e9436/MAImp.r")
source(con)

the error code is the following
Error in source(con) : cannot open the connection
In addition: Warning message:
In source(con) : unsupported URL scheme

How can I amend the code that it will also work on my MAC ?

many thanks

martin
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