This is the command I used:
sudo apt-get install python3.7
But I got:
Reading package lists... Done
Building dependency tree
Reading state information... Done
Note, selecting 'python3.7-2to3' for regex 'python3.7'
Note, selecting 'libpython3.7-stdlib' for regex 'python3.7'
0 upgraded, 0 newly installed, 0 to remove and 91 not upgraded.