There doesn't appear to be an LTRIM function. Here's one way to do it, using a regular expression.
/*
Function Name: ltrim
Description: Trim any spaces on the left side of a string.
Arguments:
in_string String to do the left trim on
Sample calls:
a = " ddd eee fff ";
print(ltrim(a));
c = "abcde";
print(ltrim(c));
*/
ltrim = Function( {in_string},
{Default Local},
// Use the regular expression "^ *" which means start at the beginning of the string
// and match any number of sequential spaces
start_nonspace = length(Regex(in_string, "^ *"));
ltrim_string = substr(in_string, (start_nonspace+1));
ltrim_string;
);