code: public static ParameterizedBy element(Class<? extends By> byClass, String variableName) {
          return new ParameterizedBy(byClass, variableName);
      }
docs: Creates a {@link org.openqa.selenium.By} that uses a variable for its value.
  
  Example:
  <code>
  given(...)
  .when(click(element(ById.class, "id-variable")))
  .then(...)
  .end();
  </code>
  
  @param byClass
  @param variableName
  @return