Syntax:  SET LANGUAGE OVERVIEW MINIMUM LINES number defined_language

  Specifies the minimum number of lines an overview line must hide

  For example, if the value is 5, then a line hides other lines only if
  there are at least five lines to hide.  This command helps you to
  avoid having very small source-line groups, which avoids many
  expansion levels.  The default minimum lines to hide is 1.