Help with Trigger Compile Error: Method does not exist or incorrect signature: [MAP<Id,AccountTeamMember>].containsKeys(Id)

Question

I am VERY new to apex coding and am trying to figure out why the trigger below gets the "Compile Error: Method does not exist or incorrect signature: [MAP].containsKeys(Id) at line 10 column 13". I also want to make sure I test this properly. I will include the test class below too.

TRIGGER

trigger DeleteATM on Account(after insert, after update) {

    map<Id,AccountTeamMember> account2TeamMemberMap = new map<Id,AccountTeamMember>();
    for(AccountTeamMember mem : [Select Id, AccountId From AccountTeamMember Where TeamMemberRole = 'Customer Success Manager' and AccountId In : trigger.new]){
        account2TeamMemberMap.put(mem.AccountId, mem);
    }

    list<AccountTeamMember> members2Delete = new list<AccountTeamMember>();
    for(Account acc: Trigger.new){
        if (account2TeamMemberMap.containsKeys(acc.Id) && acc.Customer_Success_Manager__c == null) {
            members2Delete.add(account2TeamMemberMap.get(acc.Id));
        }
    }
    delete members2Delete;
}

TEST CLASS

@isTest
Public class RemoveCSMTest {
    Static testMethod void insertNewAccount() {
        Account Cre = new Account();
        Cre.Market__c = 'Houston';
        Cre.Business_Unit__c = '334';
        Cre.Name = 'Test CSM2';
        Cre.Customer_Success_Manager__c = '005A0000000SAC0';
        Insert cre;
        List<Account> a = [SELECT Id, Name, Customer_Success_Manager__c FROM Account WHERE Name = 'TestCSM2']; 
        for (Account accs : a){
            accs.Customer_Success_Manager__c=NULL;
            Update accs;
        }
    }
}

Answer 1

This is just a typo. the method is containsKey(), you have containsKeys(). Try removing the 's'

account2TeamMemberMap.containsKey(acc.Id)