Input type recognition

def input_type(mystr):
    tr=mystr.isdigit()
    fr=324
    count=0
    flag=-1
    flag1=0
    for char in mystr:
        flag+=1
        if char==".":
            count+=1
            flag1=flag
    if tr==True:
        return "integer"    
    elif count==1:
        tr=mystr[:flag1].isdigit()
        fr=mystr[flag1+1:].isdigit()
        if tr==True and fr==True:
            return "float"
    elif mystr=="True" or mystr=="False":
        return "boolean"
    else:
        return "string"