Copy value from one field to another

Copy value from one field to another

This must be the single most simple task for a Custom Function, yet it is neither explained in the CRM documentation (help), these forums or any YouTube tutorial videos. I have spent about half a day searching for it. I'd also like to point out that users have been asking for this to be implemented as a more simple workflow automation for years ( https://help.zoho.com/portal/en/community/topic/can-i-use-a-workflow-to-update-a-field-with-the-value-of-another-field-or-of-the-current-date ).

So in order to get this done I have taken a look at Deluge, but have not been successful so far. I have copied the code used in this YouTube video ( https://www.youtube.com/watch?v=TZVYsWL8yeg ) and got working what he did. He takes the Lead ID of a record in the Leads module and (on creation) puts it into a custom field named SysLead_ID:

*** Arguments ***
Name: myLeadID Value: Lead Id

*** Code ***
void copySysLeadID (int myLeadID)

strLeadID=input.myLeadID.toString();
crmRsp = zoho.crm.updateRecord("Leads",strLeadID,{ "SysLead_ID" : strLeadID });

Just for the sake of staying with this example, I would now like to take the data entered into the Street field of the Lead record and put it into the custom field SysLead_ID of the same record.

However, apparently fetching Lead ID is simpler than fetching the content of a field, because just substituting strLeadID for a field name (even when I put it into Arguments) didn't work. I think the value of the Street field has to be fetched with an additional 1-2 lines of code not unlike described here ( https://help.zoho.com/portal/en/community/topic/coping-data-from-one-field-to-another-in-same-module ). I still didn't get it to work, though, because his use case is too special.

Can anyone please help me?