BaseExample.config

<configuration xmlns:patch="http://www.sitecore.net/xmlconfig/" 
  xmlns:set="http://www.sitecore.net/xmlconfig/set/" 
  xmlns:role="http://www.sitecore.net/xmlconfig/role/" 
  xmlns:environment="http://www.sitecore.net/xmlconfig/environment/">
  <sitecore role:require="Standalone or ContentManagement">
  </sitecore>
</configuration>

TransformExample.config

<?xml version="1.0"?>
<configuration xmlns:xdt="http://schemas.microsoft.com/XML-Document-Transform">
  <appSettings>
    <add xdt:Transform="Insert" key="environment:define" value="Dev"/>
  </appSettings>
</configuration>

UnicornExample.config

<configuration xmlns:patch="http://www.sitecore.net/xmlconfig/" xmlns:set="http://www.sitecore.net/xmlconfig/set/" xmlns:role="http://www.sitecore.net/xmlconfig/role/" xmlns:environment="http://www.sitecore.net/xmlconfig/environment/">
  <sitecore role:require="Standalone or ContentManagement">
    <unicorn>
      <configurations>
        <configuration name="Company.Project.DotCom" description="Files and items for the DotCom website." dependencies="Company.Website" extends="Company.Base">
          <predicate type="Unicorn.Predicates.SerializationPresetPredicate, Unicorn" singleInstance="true">
            <include name="Forms" database="master" path="/sitecore/Forms/Company/DotCom" environment:require="Int or Tst or Prd">
              <exclude childrenOfPath="usa/*" />
            </include>
            <include name="Forms" database="master" path="/sitecore/Forms/Company/DotCom" environment:require="Dev" />
            <include name="Content" database="master" path="/sitecore/content/Company/DotCom" environment:require="Int or Tst or Prd">
              <exclude path="usa/Home" />
            </include>
            <include name="Content" database="master" path="/sitecore/content/Company/DotCom" environment:require="Dev" />
          </predicate>
          <dataProviderConfiguration enableTransparentSync="true" type="Unicorn.Data.DataProvider.DefaultUnicornDataProviderConfiguration, Unicorn" singleInstance="true" environment:require="Dev" />
        </configuration>
      </configurations>
    </unicorn>
  </sitecore>
</configuration>