Combine letters of a string with a given number of siblings

Question

With a given string I need to combine the chars of the word only with a certain number of siblings, i.e., Hello with 3, the combinations will be: Hel, ell, llo.

a was trying with the combination and permutation function, but I can't control how the function combines the chars.

Answer 1

>>> def substrings(s, length=3):
...     yield from (s[i:i + length] for i in range(len(s) - length + 1))
...
>>>
>>> list(substrings("Hello"))
['Hel', 'ell', 'llo']
>>> list(substrings("Hello", length=2))
['He', 'el', 'll', 'lo']
>>> list(substrings("Hello", length=5))
['Hello']
>>> list(substrings("Hello", length=6))
[]