What dictionary method can be utilized to access the entries in a dictionary variable with a name of parts

Report all segments of identity by descent longer than 20 polymorphisms between pairs of individuals in the following cohort of 15 individuals across 49 polymorphisms: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 numeric input 2 points possible (graded) you have 2 attempts to complete the assignment below. for example if the sequence is "bcd", which occurs in "abcdef" , the starting point would be 2 (b), and the finishing point would be 4(d). individuals 7,10 between positions