[Tutor] Roman Numeral - To - Digital Converter

[Alan Gilfoy]

Roman Numeral - To - Digital Converter

So far, I'm coming along OK with the code that runs the conversions,  
assuming the user gives me a proper input. (A string of capital  
letters I, V, X, L, C, D, M)

However, not every input someone gives the function is goign to be  
properly formatted like that.

So:

1. How do I have my function "screen" an input string for characters  
that aren't I,V,X,L,C,D or M?
2. If any of the characters in the string are merely lowercase  
i,v,x,l,c,d, or m, how would I tell Python to capitalize those and go  
on with working the function?
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