Uninitialized constant Net::LDAP::LDAP_MOD_REPLACE

I am trying to write a buby script that changes an ldap password. The
chngo = lines generates:

$hashedpwd = hasho($newpassword) # gethased value of new password
chango = [
Net::LDAP.mod(Net::LDAP::LDAP_MOD_REPLACE,“userPassword”,[$hashedpwd]),
]

./passwordManagement.rb:57:in `getConn’: uninitialized constant
Net::LDAP::LDAP_MOD_REPLACE (NameError)
Any thoughts on what the correct syntax would be fot that constant?