As your parent already noted, thinking of it as a sequence of code points goes wrong when you need to truncate a string in between a base and a combining character.
It is composed of two code points: U+0064 and U+034A. The second code point is a combining character. The two code points together form one glyph. The term "character" is confusing because people use different definitions for it, I avoid using it, but the term Unicode code point is very clear.
Python 3's strings is a sequence of code points. The above string is represented like this:
>>> print("d\u034A")
d͊
>>> len("d\u034A")
2
Truncating between the base and combining code points works as expected:
d͊
It is composed of two code points: U+0064 and U+034A. The second code point is a combining character. The two code points together form one glyph. The term "character" is confusing because people use different definitions for it, I avoid using it, but the term Unicode code point is very clear.
Python 3's strings is a sequence of code points. The above string is represented like this:
Truncating between the base and combining code points works as expected: