import re
text = "the quick brown fox jumps over the lazy dog"
print( re.sub(r"(\S)(\s*)(\S)", lambda x: f'{x.group(1).lower()}{x.group(2)}{x.group(3).upper()}', text) )
# tHe QuIcK bRoWn FoX jUmPs OvEr ThE lAzY dOg
aW1wb3J0IHJlCnRleHQgPSAidGhlIHF1aWNrIGJyb3duIGZveCBqdW1wcyBvdmVyIHRoZSBsYXp5IGRvZyIKcHJpbnQoIHJlLnN1YihyIihcUykoXHMqKShcUykiLCBsYW1iZGEgeDogZid7eC5ncm91cCgxKS5sb3dlcigpfXt4Lmdyb3VwKDIpfXt4Lmdyb3VwKDMpLnVwcGVyKCl9JywgdGV4dCkgKQojIHRIZSBRdUljSyBiUm9XbiBGb1ggalVtUHMgT3ZFciBUaEUgbEF6WSBkT2c=