Logic In operator
The in operator is used to detect if a provided value (left) is contained in an enumerable data type (right). This is actually a detection whether a variable is a member of a defined group.
Enumerable data types are list, dict, string, IP prefix lists.
In case a variable is a group member, it returns True, otherwise False.
XML representation of the logic_is_in block
<xml xmlns="http://www.w3.org/1999/xhtml">
<block type="logic_is_in">
<value name="A">
<block type="ip">
<field name="IP">192.168.0.0</field>
</block>
</value>
<value name="B">
<block type="ip_prefix_list">
<field name="IP_PREFIX_LIST">cac2ac66-84b0-4d50-918e-22a70d55ac56</field>
</block>
</value>
</block>
</xml>

“In” - contains

“In” - example
In operator is used in If statement to detect whether the given IP address is present in Bogon prefix list.