Remove then keywords from if statements (#51)

Co-authored-by: Herwin <herwinw@users.noreply.github.com>

Author: herwinw

lib/xmlrpc/client.rb

@@ -44,7 +44,7 @@ module XMLRPC # :nodoc:
   #
   #     server = XMLRPC::Client.new("www.ruby-lang.org", "/RPC2", 80)
   #     ok, param = server.call2("michael.add", 4, 5)
-  #     if ok then
+  #     if ok
   #       puts "4 + 5 = #{param}"
   #     else
   #       puts "Error:"

lib/xmlrpc/parser.rb

@@ -205,7 +205,7 @@ def nodeMustBe(node, name)
           raise "error"
         end
 
-        if not cmp then
+        if not cmp
           raise "wrong xml-rpc (name)"
         end
 
@@ -217,14 +217,14 @@ def hasOnlyOneChild(node, name=nil)
         if node.childNodes.to_a.size != 1
           raise "wrong xml-rpc (size)"
         end
-        if name != nil then
+        if name != nil
           nodeMustBe(node.firstChild, name)
         end
       end
 
 
       def assert(b)
-        if not b then
+        if not b
           raise "assert-fail"
         end
       end
@@ -436,7 +436,7 @@ def methodCall(node)
         assert( (1..2).include?( node.childNodes.to_a.size ) )
         name = methodName(node[0])
 
-        if node.childNodes.to_a.size == 2 then
+        if node.childNodes.to_a.size == 2
           pa = params(node[1])
         else # no parameters given
           pa = []

lib/xmlrpc/utils.rb

@@ -46,15 +46,15 @@ def set_parser(parser)
 
     def create
       # if set_writer was not already called then call it now
-      if @create.nil? then
+      if @create.nil?
         set_writer(Config.default_writer.new)
       end
       @create
     end
 
     def parser
       # if set_parser was not already called then call it now
-      if @parser.nil? then
+      if @parser.nil?
         set_parser(Config.default_parser.new)
       end
       @parser