while (<>) {
   chomp;

   while (
      /
         (\w+)                      # An identifier.
         \s* = \s*                  # Equal with opt spaces.
         (
            (?:
               (?! \s+ \w+ \s* = )  # Stop if we see the next formula.
               .                    # A chararacter.
            )+
         )
      /xg
   ) {
      my ($name, $expr) = ($1, $2);

      $expr = substr($expr, 1, -1)
         if substr($expr, 0, 1) eq "'";

      print("var: $name, expr: $expr\n");
   }
}