Looks like the tab width. Old-school Unix programs assume that a tab is eight characters wide, and they mixed tabs and spaces to achieve the desired output. New-school programs allow you to configure the tab width, and then they just use tabs.
It looks as if your tab width was set to 4 but the
more program that you used assumed a tab width of 8.
I think Atom has a setting that allows you to indent using spaces, not tabs.
Theoretically, the new-school approach has advantages, but you have to distinguish between indentation (used inside an if or a loop) and alignment (used to move the beginning of the current line to a specific spot in the previous line). Consider indentation:
If you use one tab character to indent the body of the if statement, then you can select a tab width of 4 and I can select a tab width of 8, and we can both edit the same file even though we prefer different indentation levels.
But of course, this does not work for alignment – in your example, the number of spaces at the beginning of the second line is exactly determined by the number of characters
x = call_function(.
It’s theoretically possible to cater for both: use tabs for indentation, then follow with spaces for alignment, if alignment is desired. It’s harder to figure out which part of the line is indented and which part is aligned, but it’s theoretically possible.