list all the elements that pecede a certain element in python array

I have an array in python that has letters as strings and a comma as a string also. I have managed to find code that finds all the letters that come before that comma letter, there are other comma letters and i would like to iterate to list every letter that comes before the commas in the array here is what i got so far

##THE ARRAY IS THIS ONE
myarray=['G', 'o', 'T', ',', 'I', 't', 'B', ',', 'M', 'N', 'R', ',', 'K', 'F', 'P', ',', 'M', 'F', 'I', 'H', ',', 'A', 'H', ',']
temp = myarray.index(",")
res = myarray[:temp]
print(res)

##tHE CODE ABOVE outputs ['G','o','T'], is there a way in which i can iterate through all elements in 
the array listing every letter that comes before the commas