user input and error handling herethe line eval(sis equivalent to writing + but using eval gives much more flexibilityof coursesince the string is stored in variable and can be read as input small python program using eval can be quite flexible considerfor instancethe following code eval(input('operand ') eval(input('operand ') print( '{type( ){type( )becomes {type( )with value{ }'this code can handle multiple input types if we save the code in file add_input py and run it from the terminalwe canfor instanceadd integer and float numbersas interminal terminalpython add_input py operand operand becomes with value or two listsas followsterminal terminalpython add_input py operand [ , operand [- , , becomes with value [ - we could achieve similar flexibility with conventional type conversionthat isusing float( )int( )and so onbut that would require much more programming to correctly process the input strings the eval function makes such flexible input handling extremely compact and efficientbut it also quickly breaks if the input is slightly wrong consider the following examplesterminal terminalpython add_input py operand ( , operand [ , traceback (most recent call last)file "add_input py"line in typeerrorcan only concatenate tuple (not "list"to tuple terminalpython add_input py