Info is confusing and test needs improvement.

"Two or more characters of one string can correspond to one character of another string, but not vice versa."

This line didn't specify "which one of the string" can correspond to one character of the other string. And nor can you tell it from the basics tests cause it only shows:

isometric_strings("foo", "bar") == False

but no expected answer for:

isometric_strings("bar", "foo") == ?

Which to my understanding should be True.

Suggestion:

1. Use "Two or more characters in the first string can correspond to same character of the second string, but not vice versa."

2. Add "isometric_strings("bar", "foo") == True" to examples so readers can tell the difference.