Structure of norepinephrine, rendered with hand-written or mol2chemfig-generated chemfig code. The code in A was hand-written and uses chemfig’s dedicated syntax for specifying rings (see lines 7–14). The code in B was generated with the mol2chemfig command shown at the top; it does not use chemfig’s ring syntax but instead treats the ring much like a regular branch. Each line of code specifies one bond; the number in the line-end comment specifies the atom that this bond connects to. While the code examples use line breaks and indentation for clarity, this is not required; whitespace is insignificant to chemfig.