+`company-begin-backend' to start itself in that case.
+
+Grouped back-ends:
+
+An element of `company-backends' can also itself be a list of back-ends,
+then it's considered to be a \"grouped\" back-end.
+
+When possible, commands taking a candidate as an argument are dispatched to
+the back-end it came from. In other cases, the first non-nil value among
+all the back-ends is returned.
+
+The latter is the case for the `prefix' command. But if the group contains
+the keyword `:with', the back-ends after it are ignored for this command.
+
+The completions from back-ends in a group are merged (but only from those
+that return the same `prefix')."